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<a name="Interoperability-Options"></a>
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<hr>
<a name="Options-for-interoperability-with-other-languages"></a>
<h3 class="section">2.10 Options for interoperability with other languages</h3>

<dl compact="compact">
<dd>
<a name="index-c_002dprototypes"></a>
<a name="index-Generating-C-prototypes-from-Fortran-BIND_0028C_0029-enteties"></a>
</dd>
<dt>-fc-prototypes</dt>
<dd><p>This option will generate C prototypes from <code>BIND(C)</code> variable
declarations, types and procedure interfaces and writes them to
standard output.  <code>ENUM</code> is not yet supported.
</p>
<p>The generated prototypes may need inclusion of an appropriate header,
such as <code>&lt;stdint.h&gt;</code> or <code>&lt;stdlib.h&gt;</code>.  For types which are
not specified using the appropriate kind from the <code>iso_c_binding</code>
module, a warning is added as a comment to the code.
</p>
<p>For function pointers, a pointer to a function returning <code>int</code>
without an explicit argument list is generated.
</p>
<p>Example of use:
</p><div class="smallexample">
<pre class="smallexample">$ gfortran -fc-prototypes -fsyntax-only foo.f90 &gt; foo.h
</pre></div>
<p>where the C code intended for interoperating with the Fortran code
then  uses <code>#include &quot;foo.h&quot;</code>.
</p>
<a name="index-c_002dprototypes_002dexternal"></a>
<a name="index-Generating-C-prototypes-from-external-procedures"></a>
</dd>
<dt>-fc-prototypes-external</dt>
<dd><p>This option will generate C prototypes from external functions and
subroutines and write them to standard output.  This may be useful for
making sure that C bindings to Fortran code are correct.  This option
does not generate prototypes for <code>BIND(C)</code> procedures, use
<samp>-fc-prototypes</samp> for that.
</p>
<p>The generated prototypes may need inclusion of an appropriate
header, such as <code>&lt;stdint.h&gt;</code> or <code>&lt;stdlib.h&gt;</code>.
</p>
<p>This is primarily meant for legacy code to ensure that existing C
bindings match what <code>gfortran</code> emits.  The generated C
prototypes should be correct for the current version of the compiler,
but may not match what other compilers or earlier versions of
<code>gfortran</code> need.  For new developments, use of the
<code>BIND(C)</code> features is recommended.
</p>
<p>Example of use:
</p><div class="smallexample">
<pre class="smallexample">$ gfortran -fc-prototypes-external -fsyntax-only foo.f &gt; foo.h
</pre></div>
<p>where the C code intended for interoperating with the Fortran code
then  uses <code>#include &quot;foo.h&quot;</code>.
</p></dd>
</dl>

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